Enterprise Integration Patterns
Camel supports most of the Enterprise Integration Patterns from the excellent book of the same name by Gregor Hohpe and Bobby Woolf. Its a highly recommended book, particularly for users of Camel.
Pattern Index
There now follows a list of the Enterprise Integration Patterns from the book along with examples of the various patterns using Apache Camel
Messaging Systems
How does one application communicate with another using messaging? | ||
How can two applications connected by a message channel exchange a piece of information? | ||
How can we perform complex processing on a message while maintaining independence and flexibility? | ||
How can you decouple individual processing steps so that messages can be passed to different filters depending on a set of conditions? | ||
How can systems using different data formats communicate with each other using messaging? | ||
How does an application connect to a messaging channel to send and receive messages? |
Messaging Channels
How can the caller be sure that exactly one receiver will receive the document or perform the call? | ||
How can the sender broadcast an event to all interested receivers? | ||
What will the messaging system do with a message it cannot deliver? | ||
How can the sender make sure that a message will be delivered, even if the messaging system fails? | ||
What is an architecture that enables separate applications to work together, but in a de-coupled fashion such that applications can be easily added or removed without affecting the others? |
Message Construction
How can messaging be used to transmit events from one application to another? | ||
When an application sends a message, how can it get a response from the receiver? | ||
How does a requestor that has received a reply know which request this is the reply for? | ||
How does a replier know where to send the reply? |
Message Routing
How do we handle a situation where the implementation of a single logical function (e.g., inventory check) is spread across multiple physical systems? | ||
How can a component avoid receiving uninteresting messages? | ||
How can you avoid the dependency of the router on all possible destinations while maintaining its efficiency? | ||
How do we route a message to a list of (static or dynamically) specified recipients? | ||
How can we process a message if it contains multiple elements, each of which may have to be processed in a different way? | ||
How do we combine the results of individual, but related messages so that they can be processed as a whole? | ||
How can we get a stream of related but out-of-sequence messages back into the correct order? | ||
How can you maintain the overall message flow when processing a message consisting of multiple elements, each of which may require different processing? | ||
How do you maintain the overall message flow when a message needs to be sent to multiple recipients, each of which may send a reply? | ||
How do we route a message consecutively through a series of processing steps when the sequence of steps is not known at design-time and may vary for each message? | ||
How can I throttle messages to ensure that a specific endpoint does not get overloaded, or we don't exceed an agreed SLA with some external service? | ||
How can I sample one message out of many in a given period to avoid downstream route does not get overloaded? | ||
How can I delay the sending of a message? | ||
How can I balance load across a number of endpoints? | ||
To use Hystrix Circuit Breaker when calling an external service. | ||
To call a remote service in a distributed system where the service is looked up from a service registry of some sorts. | ||
How can I route a message to a number of endpoints at the same time? | ||
How can I repeat processing a message in a loop? |
Message Transformation
How do we communicate with another system if the message originator does not have all the required data items available? | ||
How do you simplify dealing with a large message, when you are interested only in a few data items? | ||
How can we reduce the data volume of message sent across the system without sacrificing information content? | ||
How do you process messages that are semantically equivalent, but arrive in a different format? | ||
How can I sort the body of a message? | ||
Script | How do I execute a script which may not change the message? | |
How can I validate a message? |
Messaging Endpoints
How do you move data between domain objects and the messaging infrastructure while keeping the two independent of each other? | ||
How can an application automatically consume messages as they become available? | ||
How can an application consume a message when the application is ready? | ||
How can a messaging client process multiple messages concurrently? | ||
How can multiple consumers on a single channel coordinate their message processing? | ||
How can a message consumer select which messages it wishes to receive? | ||
How can a subscriber avoid missing messages while it's not listening for them? | ||
How can a message receiver deal with duplicate messages? | ||
How can a client control its transactions with the messaging system? | ||
How do you encapsulate access to the messaging system from the rest of the application? | ||
How can an application design a service to be invoked both via various messaging technologies and via non-messaging techniques? |
System Management
How can we effectively administer a messaging system that is distributed across multiple platforms and a wide geographic area? | ||
How can you route a message through intermediate steps to perform validation, testing or debugging functions? | ||
How do you inspect messages that travel on a point-to-point channel? | ||
How can we effectively analyze and debug the flow of messages in a loosely coupled system? | ||
How can I log processing a message? |
For a full breakdown of each pattern see the Book Pattern Appendix